A cooker is a household appliance that uses gas, electricity, etc. to cook food. A cooker that uses gas is provided with a burner that combusts gas to heat a container in which food is stored to cook the food. In general, the burner includes a burner body that supplies gas, a burner head coupled to the top end of the burner body, a burner cap defining combustion holes together between the burner head, and a spark plug for igniting gas discharged through the combustion holes.